Hi there I am planning to do a temperature based PWM control ciruit.
The requirements are:
20mA source/sink
5V powered and ~5V out (voltage out not too important as long as its high impedance)
scales from 50-95% PWM with temperature
small board size (smaller = better but no actual limit)
2kHz +/-20% (*edit*)
no software
would like to be able to set the top (95% PWM) and bottom (50% PWM) temperature
I was planning to do this with a 555timer and an NTC/PTC. I figured I could use a pot to set a minimum duty cycle, but working out the resistance values is proving to be a pain.
Then I would put a schmitt trigger on the output to get my high impedance and required current.
I was wondering if anyone else would go about this differently.
The requirements are:
20mA source/sink
5V powered and ~5V out (voltage out not too important as long as its high impedance)
scales from 50-95% PWM with temperature
small board size (smaller = better but no actual limit)
2kHz +/-20% (*edit*)
no software
would like to be able to set the top (95% PWM) and bottom (50% PWM) temperature
I was planning to do this with a 555timer and an NTC/PTC. I figured I could use a pot to set a minimum duty cycle, but working out the resistance values is proving to be a pain.
Then I would put a schmitt trigger on the output to get my high impedance and required current.
I was wondering if anyone else would go about this differently.
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